<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
</head>
<body>
<script>
    //传入一个角度 返回对应的弧度
    function degToArc(num){
        //360度=Math.PI*2
        //1度=Math.PI*2/360=Math.PI/180
        //x度=Math.PI/180*num;
        return Math.PI/180*num;
    }
</script>
</body>
</html>